2.5.8 Understanding origin of minimum "24"

[jamieherrera]

Apologies if this is a repeat from other 2.5.8 questions... I've looked at over 15 and can't find any with this question. If I missed it please add here and feel free to close as a repeat of that issue #.

2.5.5 Target Size (enhanced) explains that the 44 x number is a rough equivalent of the pad of a finger. Could you add a sentence about where the decision of 24 px came from for 2.5.8 Target Size (Minimum)? I may have seen in this forum or related blog from a W3C member that the number "24" came from the pixel size of the size of a (default size) mouse pointer. I can't find the source now and that may not be entirely accurate; i would rather quote the Understanding document for the origin for "24 px" (and not 16 or 22 or 28 ...).

As an aside, the Related Resources research appears to copy over the same research article as from 2.5.5. I only had access to the abstract; are there additional resources that could guide why the 24 px minimum was determined to be the number to use?

Thanks in advance.

[bruce-usab]

@jamieherrera -- I was "in the room" when AGWG picked 24px but I cannot tell you the genesis. But why does that matter?
Are you having difficulty implementing or enforcing? Obviously, we wanted to go as large as we could while picking something feasible for all technologies all the time.

Thinking about in-line graphics, since those are common, 12pt is 16px and 24px is half-again larger. So that is about as large a target size could be without hitting the line above/below. 24px targets in a line of text is not unreasonable.

The Related Resources are the best we could find. Yes, many academic articles are behind a pay wall. I don't believe you will be able to find an authoritative citation for 24px over 16 or 22 or 28.